I have an '80 Chev short/step that originally had a 6 w/a 3sp on the column. The previous owner put a 283 with what I believe is a Saginaw 4sp in it. I'm hauling out the 283 and putting in a crate vortec 350, and I'm trying to ID the gear box. It's mated to an aluminum bell housing and the clutch pivot rod ball-stud is threaded into the bell housing instead of the engine block. The only reason I think it's a Sag is because doing a search here on Hotrodders there was a link that spoke to the Sags having grooves on the input shaft ID'ing the ratios.
I'd like to find out what this trans/bellhousing came out of and if it's a good match for this engine. The input shaft is 1 1/8 dia, 10 spline with three grooves. I have the GM casting numbers but can't find anything that will ID it to a vehicle.

Thanks...

Cast Iron case is Saginaw
Aluminum case is Muncie
Muncie is 4 speed only; coarse spline is M20 or M21
Saginaw came 3 and 4 speed. 4 speed trans always have 3 linkage arms on the side of the case.
Borg Warner SuperT10 is a fine spline input shaft trans; not what you have.

Got a picture of it?

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Saginaw's used a 7 bolt side cover. I believe the Muncies were 8 or 9. The Saginaw also had the reverse lever in the side cover, as the Muncie was in the maincase.

The Saginaw's were made in 5 different ratios, the highest was something like 2.11 1st gear, the lowest was 3.50 1st gear. The only 1 I remember of the top of my head is the 3.50 had 3 lines around the input shaft.

Not to may floating around this part of the world, as that is the popular transmission among the IMCA racers, in 3 different classes.

I used a saginaw 4 speed behind my warmed up 235 in a 1950 Chevy truck I had 10- 12 years ago


here is what I found for the grooves in the input shaft of the saginaw tranny;

Saginaw 4-speed 1st 2nd 3rd 4th

No lines 2.84 2.01 1.35 1.00
1 Line 2.54 1.80 1.44 1.00
2 Lines 3.11 2.20 1.47 1.00
3 Lines 3.50 2.47 1.65 1.00

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At the Bonneville Salt Flats... 130mph is known as First gear ...............

Saginaw has all three shift levers mounted on the removable side cover.